In the semi-conductor manufacturing field and the like, there is conveyance devices each including multijoint arms as a conveyance means for conveying a conveyance object such as a wafer or glass substrate under vacuum or in a process gas atmosphere, for example. Extending and retracting or turning the arm, such a conveyance device moves a distal end of the arm to an arbitrary position and conveys the conveyance object. Some arms allow three-dimensional movement by extending and retracting or turning in a horizontal direction with a rotational power in the horizontal direction and moving up and down in a vertical direction. In this case, a drive portion that drives the arm needs a mechanism for generating the rotational power in the horizontal direction and a mechanism for moving up and down in the vertical direction.
For example, Patent Document 1 describes a conveyance device including a casing that houses main parts of a drive portion and a drive-portion support frame housed in the casing. The drive-portion support frame supports a plurality of motors and the like for extending/retracting and turning arms and the like. The drive-portion support frame moves up and down within the casing along linear guide rails provided in the vertical direction via a ball screw mechanism by the motors provided at the bottom portion of the casing. When the drive-portion support frame moves up and down, all the arms move up and down (for example, see paragraph [0016] and FIG. 1 of Patent Document 1).
To the upper portion of the casing, a base plate is connected. The base plate is provided in an opening portion formed in a scaffold (fixing portion) in the vacuum atmosphere. That is, the drive portion is supported by the base plate such that (the drive portion of) the conveyance device is hung from the opening portion formed in the scaffold.